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Smoothed particle hydrodynamics approach for modelling submerged granular flows and the induced water wave generation Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2024-02-13 A. Mahallem, M. Roudane, A. Krimi, S. A. Gouri, A. Allali
In this study, we develop a Smoothed Particle Hydrodynamics (SPH) 2D-model for simulating fully submerged granular flows and their arising water waves. The granular particles are characterised by a...
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On stratified flow over a topographic ridge in a rotating annulus Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2024-02-13 Kial D. Stewart, Callum J. Shakespeare
Interactions between the rotating stratified oceanic and atmospheric flows and topography play a fundamental role in Earth's climate. Here we use laboratory experiments in a differentially-heated r...
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Balanced convective circulations in a stratified atmosphere. Part II: circulations in the presence of radiation and the non-traditional coriolis terms Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2023-12-29 David H. Marsico, Joseph A. Biello, Matthew R. Igel
The full Coriolis force consists of terms proportional to the sine and cosine of latitude. The latter, referred to as the non-traditional Coriolis terms, couple the zonal and vertical momentum equa...
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Rotating convective turbulence in moderate to high Prandtl number fluids Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2023-12-06 Jewel A. Abbate, Jonathan M. Aurnou
Rotating convective turbulence is ubiquitously found across geophysical settings, such as surface and subsurface oceans, planetary atmospheres, molten metal planetary cores, magma chambers, magma o...
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Zonostrophic instabilities in magnetohydrodynamic Kolmogorov flow Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2023-11-06 Azza M. Algatheem, Andrew D. Gilbert, Andrew S. Hillier
A classic stability problem relevant to many applications in geophysical and astrophysical fluid mechanics is that of Kolmogorov flow, a unidirectional purely sinusoidal velocity field written here...
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Scales of vertical motions due to an isolated vortex in ageostrophic balanced flows Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2023-10-31 William J. McKiver
Here we consider a model of an isolated vortex to understand the vertical dynamics induced by mesoscale eddies in the ocean. We use the analytical solutions to a balanced model for an ellipsoid of ...
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Solitary wave scattering by segmented arc-shaped breakwater Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2023-10-31 Jianming Miao, Yu Han, Sen Liu, Zhenfeng Zhai
An analytical solution is presented to study a plane solitary wave propagating past a concentric segmented arc-shaped breakwater using the matched eigenfunction and separation of variable methods. ...
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Can the observable solar activity spectrum be reproduced by a simple dynamo model? Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2023-10-20 R. Okatev, P. Frick, D. Sokoloff
The temporal spectrum of the solar activity is more than just the main cycle. It contains different timescales, which can be considered as continuous components of the activity spectrum. The possib...
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Quasi-geostrophic vortex vertical alignment in near collapse interactions Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2023-08-10 Jean N. Reinaud, Xavier Carton
We consider a three-vortex interaction which leads to the vertical alignment of two like-signed quasi-geostrophic vortices in a continuously stratified, rotating fluid. The interaction is close to ...
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On Saturn's six-sided polar jet stream Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2023-07-24 Adrian Constantin
We derive the nonlinear governing equations for stratified circumpolar atmospheric jet flow in Saturn's upper troposphere. An exact solution is obtained in the material (Lagrangian) framework, by s...
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Self-adjointness of sound-proof models for magnetic buoyancy Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2023-07-19 J. B. Moss, T. S. Wood, P. J. Bushby
An ideal magneto-hydrodynamic fluid, whether fully compressible or incompressible, is a Hamiltonian system. This implies that the equations describing perturbations to any static state are self-adjoint, a fact that is useful in obtaining stability criteria. To describe weakly compressible flows, there are a number of “sound-proof” models that eliminate sound waves by making approximations to the governing
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Barrier and bottom topography effects on hydroelastic response of floating elastic plate in a two-layer fluid Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2023-07-18 N. M. Prasad, R. M. Prasad, Prashant Kumar, Pulkit Kumar, Chandra Mani Prasad
The prime intention of this article is to investigate the effect of variable bottom topography and a bottom-sitting porous barrier on the hydroelastic response of an elastic plate floating on a two-layer fluid using small amplitude wave theory. Galerkin's single-mode approximation in each layer for variable bottom topography and the method of eigenfunction expansion for the fluid region of uniform
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Filaments of uniform quasi-geostrophic potential vorticity in pure strain Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2023-07-16 Jean N. Reinaud
Three-dimensional filaments of quasi-geostrophic potential vorticity are generic features of atmospheric and oceanic flows. They are often generated during the strong interactions between three-dimensional quasi-geostrophic vortices. They contribute to a direct cascade of enstrophy in spectral space. These filaments correspond to shear zones. Therefore they may be sensitive to shear instabilities akin
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The Earth's rotational modes revisited Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2023-06-30 B. Seyed-Mahmoud
In the conventional treatment of the Earth's rotational dynamics using the Earth's angular momentum description (AMD), it is customary to assume that the velocity/displacement of a mass element in the liquid core (LC) has a displacement as well as an explicit rigid rotation component in addition to the uniform (solid-body) rotation. This makes for a very complex set of non-linear differential equations
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A shallow layer laboratory model of large-scale atmospheric circulation Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2023-06-09 Andrei Sukhanovskii, Elena Popova, Andrei Vasiliev
A new shallow layer laboratory model of global atmospheric circulation is realised and studied by experiments and numerical simulations. A shallow rotating cylindrical fluid layer of 30 mm thickness and 690 mm diameter, with a localised heater at the bottom periphery and localised cooler in the central part of the upper boundary is considered. The rim heater imitates the equator heating and disc cooler
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The influence of flexible bottom on wave generation by an oscillatory disturbance in the presence of surface tension Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2023-05-15 Selina Hossain, Arijit Das, Soumen De
The two-dimensional problem of wave generation by a time-harmonic pressure distribution on the surface in a finite-depth ocean is studied in this article. Here, it is considered that the ocean has a flexible base, which is modelled as a thin elastic plate and is governed by the Euler–Bernoulli beam equation. The effect of surface tension at the free surface is also taken into account. Within the framework
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Analysing the impact of bottom friction on shallow water waves over idealised bottom topographies Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2023-05-12 Chang Liu, Antwan D. Clark
Analysing the impact of bottom friction on shallow water waves over bottom terrains is important in areas including environmental and coastal engineering as well as the oceanic and atmospheric sciences. However, current theoretical developments rely on making certain limiting assumptions about these flows and thus more development is needed to be able to further generalise this behaviour. This work
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Scattering of water waves by two thin vertical barriers over shelf bottom topography Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2023-05-02 Naveen Kumar, Amandeep Kaur, S. C. Martha
In this paper, water waves interaction with two thin vertical barriers over shelf bottom topography is analysed using linearised wave theory. The associated mixed boundary value problem is solved with the aid of method involving eigenfunction expansions of the velocity potential and orthogonality relation of the eigenfunctions. Further, the resulting system of algebraic equations is solved using the
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Dynamics of the coherent structure for incompressible fluid flow in turbulent boundary layers Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2023-04-26 R. S. Selim
We consider the nonlinear interaction system of waves to identify discrete clusters of resonant triads, which are classified on the basis of the resonance condition. This study is conducted to investigate the coherent structure of incompressible fluid flow in the turbulent boundary layer. The discrete wave turbulence is characterised by weakly nonlinear interaction modes for amplitude Tollmien Schlichting
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On the mathematical theory of plumes Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2023-04-06 R. S. Garvey, A. C. Fowler
ABSTRACT We reconsider the theory of turbulent plume formation provided by Schmidt (Citation1941a,Citationb) and its integral formulation, particularly that of Morton et al. (Citation1956). A particular issue for the correct formulation of a mathematical theory is whether the plume is taken to have finite or infinite width, and whether the entrainment rate is prescribed or deduced. Fox (1970) showed
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Wave radiation by a horizontal circular cylinder in a three-layer fluid Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2023-02-22 Minakshi Ghosh, Dilip Das
To construct cylindrical structures like circular pipe bridges or tunnels submerged in the almost still density-stratified ocean or seawater, the study of waves radiated by the cylinder is essential. This research solves the wave radiation problem by calculating non-dimensionalized added mass and damping coefficients to the mass of the fluid displaced by the submerged horizontal cylinder in either
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Semi-analytical solutions of shallow water waves with idealised bottom topographies Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2023-02-06 Chang Liu, Antwan D. Clark
Analysing two-dimensional shallow water equations with idealised bottom topographies have many applications in the atmospheric and oceanic sciences; however, restrictive flow pattern assumptions have been made to achieve explicit solutions. This work employs the Adomian decomposition method (ADM) to develop semi-analytical formulations of these problems that preserve the direct correlation of the physical
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Astrophysical magnetic fields: from galaxies to the early universe Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2022-12-22 Axel Brandenburg
Published in Geophysical & Astrophysical Fluid Dynamics (Vol. 116, No. 5-6, 2022)
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The inherent instability of axisymmetric magnetostrophic dynamo models Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2022-11-30 Colin M. Hardy, Philip W. Livermore, Jitse Niesen
Recent studies have demonstrated the possibility of constructing magnetostrophic dynamo models, which describe the slowly evolving background state of Earth's magnetic field when inertia and viscosity are negligible. Here we explore the properties of steady, stable magnetostrophic states as a leading order approximation to the slow dynamics within Earth's core. For the case of an axisymmetric magnetostrophic
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Resonant growth of inertial oscillations from lee waves in the deep ocean Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2022-11-12 Pierre Labreuche, Chantal Staquet, Julien Le Sommer
The interactions between inertial oscillations (IO) and lee waves (LW) close to the bottom of the ocean and the role of IO in energy dissipation are addressed for a range of physical parameters typical of Southern Ocean conditions. Idealized numerical simulations in a vertical plane and resonant interaction theory are combined for this purpose. The lee waves are emitted by a uniform geostrophic flow
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A study of global magnetic helicity in self-consistent spherical dynamos Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2022-11-08 P. Gupta, R.D. Simitev, D. MacTaggart
ABSTRACT Magnetic helicity is a fundamental constraint in both ideal and resistive magnetohydrodynamics. Measurements of magnetic helicity density on the Sun and other stars are used to interpret the internal behaviour of the dynamo generating the global magnetic field. In this note, we study the behaviour of the global relative magnetic helicity in three self-consistent spherical dynamo solutions
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On the mother bodies of steady polygonal uniform vortices. Part I: numerical experiments Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2022-11-04 Giorgio Riccardi
ABSTRACT The existence of an integral relation between self-induced velocity of a uniform, planar vortex and Schwarz function of its boundary opens the way to understand the kinematics of the vortex by analysing the internal singularities of that function. In general, they are branch cuts and form the so-called “mother body” of the vortex, because they generate the same external velocities of the vortex
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Introduction Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2022-10-27 Radostin D. Simitev, David MacTaggart, Robert Teed, Simon Candelaresi
Published in Geophysical & Astrophysical Fluid Dynamics (Vol. 116, No. 4, 2022)
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Multiplicity in an optimised kinematic dynamo Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2022-09-28 Long Chen
Multiplicity in optimal kinematic dynamos exists for certain types of symmetry classes and boundary conditions, at least near the lowest dynamo onset Rmc. Here we investigate the NNT type dynamo generated by steady flows with impermeable boundary conditions in a cube, where the letter N or T stands for pseudo-vacuum or superconducting boundary conditions along x, y, z directions, respectively. We find
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Magnetoconvection in a rotating spherical shell in the presence of a uniform axial magnetic field Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2022-08-12 Stephen J. Mason, Céline Guervilly, Graeme R. Sarson
ABSTRACT We report simulations of thermal convection and magnetic-field generation in a rapidly-rotating spherical shell, in the presence of a uniform axial magnetic field of variable strength. We consider the effect of the imposed field on the critical parameters (Rayleigh number, azimuthal wavenumber and propagation frequency) for the onset of convection, and on the relative importance of Coriolis
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An exact threshold for separator bifurcation Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2022-06-21 C. Prior, P. F. Wyper
Reconnection involving magnetic separators is known to lead to the spontaneous generation of new separator pairs. In this work, we explore the bifurcation process for a system composed of a pair of null points with a joining separator. We begin with a simplified analytical model to derive the basic principles of bifurcation in this system and then consider models with more general separator curve geometry
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Angular momentum transfer in direct numerical simulations of a laboratory model of a tropical cyclone Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2022-06-14 Anna Evgrafova, Andrei Sukhanovskii
ABSTRACT Numerical simulations of a laboratory model of a tropical cyclone are carried out for different rotation rates. Particular attention is paid to the non-stationary stage of intensive cyclonic vortex formation. The transfer of angular momentum plays a key role in the formation of cyclonic and anticyclonic flows; therefore, a detailed analysis of the redistribution and variation of angular momentum
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Rigorous results on conserved and dissipated quantities in ideal MHD turbulence Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2022-06-13 Daniel Faraco, Sauli Lindberg, László Székelyhidi
We review recent mathematical results on the theory of ideal MHD turbulence. On the one hand, we explain a mathematical version of Taylor's conjecture on magnetic helicity conservation, both for simply and multiply connected domains. On the other hand, we describe how to prove the existence of weak solutions conserving magnetic helicity but dissipating cross helicity and energy in 3D Ideal MHD. Such
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Formation of small-scale vortices in the core of a large merged vortex Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2022-05-25 Erwan Oulhen, Jean N. Reinaud, Xavier Carton
The merger of two surface quasi-geostrophic vortices is examined in detail. As the two vortices collapse towards each other in the merging process, they trap their external fronts between them; these fronts are inserted into the final merged vortex, where they form a central, nearly parallel, sheared velocity strip, sensitive to barotropic instability. As a result, this strip breaks up into an alley
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Effects of mesoscale turbulence on the wind-driven circulation in a closed basin with topography Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2022-05-09 L. Zavala Sansón
This paper studies the effects of time-dependent, mesoscale turbulence on the wind-driven ocean circulation in a closed basin with variable topography. Numerical simulations of a single-layer fluid with finite topography at the sloping boundaries are performed. The flow is forced by a suitable combination of a steady, basin-scale wind that generates the classical western-intensified anticyclonic gyre
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Comments on: nonlinear wind-drift ocean currents in arctic regions Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2022-03-30 Adrian Constantin
ABSTRACT We clarify and correct an oversight from a recent paper, thus confirming the possibility of a nonlinear coupling of inertial oscillations and Ekman-type spiralling wind-drift currents to yield an exact solution of the system describing the leading-order dynamics of wind-drift arctic flows.
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Mean fields and fluctuations in compressible magnetohydrodynamic flows Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2022-03-07 James F. Hollins, Graeme R. Sarson, Cetin Can Evirgen, Anvar Shukurov, Andrew Fletcher, Frederick A. Gent
We apply Gaussian smoothing to obtain mean magnetic field, density, velocity, and magnetic and kinetic energy densities from our numerical model of the interstellar medium, based on three-dimensional magnetohydrodynamic equations in a shearing box 1×1×2kpc in size. The interstellar medium is highly compressible, as the turbulence is transonic or supersonic; it is thus an excellent context in which
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Geophysical fluid models with simple energy backscatter: explicit flows and unbounded exponential growth Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2022-02-14 A. Prugger, J. D. M. Rademacher, J. Yang
Motivated by numerical schemes for large-scale geophysical flow, we consider the rotating shallow water and Boussinesq equations on the whole space with horizontal kinetic energy backscatter source terms built from negative viscosity and stabilising hyperviscosity with constant parameters. We study the impact of this energy input through various explicit flows, which are simultaneously solving the
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Different approaches in scattering of water waves by two submerged porous plates over an elastic sea-floor Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2022-02-07 Ayan Chanda, Swaroop Nandan Bora
A hydroelastic model is presented here to look into the scattering of oblique water waves by two totally submerged vertical porous plates, placed at some distance from each other, in a homogeneous fluid flowing over an elastic sea-floor. Consideration of Euler–Bernoulli beam equation allows the elastic sea-floor to be approximated as a thin elastic plate whereas the porous plates follow the porous
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On the limitations of magneto-frictional relaxation Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2022-01-14 A. R. Yeates
The magneto-frictional method is used in solar physics to compute both static and quasi-static models of the Sun's coronal magnetic field. Here, we examine how accurately magneto-friction (without fluid pressure) is able to predict the relaxed state in a one-dimensional test case containing two magnetic null points. Firstly, we show that relaxation under the full ideal magnetohydrodynamic equations
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Generation of waves due to bottom disturbances in a viscous fluid Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2021-12-31 Piyali Kundu, B. N. Mandal
The generation of two-dimensional surface waves due to various types of bottom disturbances such as underwater explosions, earthquakes, or volcanic eruptions is investigated here. Assuming linear theory the present problem is formulated as an initial value problem for the wave potential function ϕ and Stokes stream function ψ. Viscosity is considered. The physical model is illustrated by a sketch.
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Eddy saturation in a reduced two-level model of the atmosphere Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2021-11-08 Melanie Kobras, Maarten H. P. Ambaum, Valerio Lucarini
Eddy saturation describes the nonlinear mechanism in geophysical flows whereby, when average conditions are considered, direct forcing of the zonal flow increases the eddy kinetic energy, while the energy associated with the zonal flow does not increase. Here, we present a minimal baroclinic model that exhibits complete eddy saturation. Starting from Phillips' classical quasi-geostrophic two-level
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Nonlinear wind-drift ocean currents in arctic regions Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2021-11-08 Adrian Constantin
We rely on the f-plane approximation to derive the nonlinear governing equations for arctic wind-drift flow in regions that are not in the vicinity of the North Pole. An exact solution is derived in the material (Lagrangian) framework, a setting suitable for the accurate description of the particle paths. This approach facilitates the identification of oscillations superimposed on a mean spiralling
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Instabilities of low-latitude easterly jets in the presence of moist convection and topography and related cyclogenesis, in a simple atmospheric model Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2021-09-17 Masoud Rostami, Vladimir Zeitlin
A simple two-layer model, the moist-convective rotating shallow water, which allows for low-cost high-resolution numerical simulations of the dynamics of the moist atmosphere in the presence of topography, is used to identify and understand dynamical processes governing the evolution of easterly waves propagating on the background of a low-latitude easterly jet crossing a land-sea boundary, a setup
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Hydrodynamic α-effect in a rotating stratified moist atmosphere driven by small-scale non-helical force Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2021-09-17 M. I. Kopp, A. V. Tur, V. V. Yanovsky
In this paper we have studied the large-scale instability in a rotating stratified moist atmosphere with a small-scale turbulence. The axis of rotation of the medium is deviated from the vertical direction. The turbulence is excited by an external small-scale force with zero helicity and a low Reynolds number. The nonlinear equations of a vortex dynamo were obtained on the basis of the method of multiscale
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Rotating thermal convection: surface turbulence observed with altimetry and thermal radiometry Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2021-09-13 Yang Zhang, Yakov Afanasyev
The surface dynamics of the rotating thermal convection are examined in finely resolved laboratory flows. Deep rotating convection creates geostrophic turbulent flow at the surface, the regime of convection relevant to flows observed in deep convection sites in the ocean or in the atmospheres of the gas giants Jupiter and Saturn. Spectral analyses reveal a dual energy cascade of the surface kinetic
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Dynamos driven by modified Beltrami flows, and a search for related planar flow dynamos Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2021-09-06 A. A. Bachtiar, R. W. James
Bachtiar, Ivers and James [Planar velocity dynamos in a sphere. Proc. R. Soc. Lond. 2006, A462, 2439–2456] showed that a planar fluid velocity v can support dynamo action in a conducting sphere, however their model p1Y22DM12 exhibited slow convergence. Seeking more planar flow dynamos, they also considered converting some historical flows to planar flows by a process they termed ‘planarising‘. In particular
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Modelling topographic waves in a polar basin Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2021-09-06 Madeleine Cockerill, Andrew P. Bassom, Andrew J. Willmott
This study is concerned with properties of freely propagating barotropic Rossby waves in a circular polar cap, a prototype model for the Arctic Ocean. The linearised shallow-water equations are used to derive an amplitude equation for the waves in which full spherical geometry is retained. Almost by definition, polar basin dynamics are confined to regions of limited latitudinal extent and this provides
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Analysis of mixing structures in the Adriatic Sea using finite-size Lyapunov exponents Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2021-08-27 Saeed Hariri
In this paper, we report on the mixing structures and transport properties of the Adriatic Sea surface, as a semi-enclosed basin of the Mediterranean Sea, from October 2006 until December 2011. Lagrangian transport models were used to simulate synthetic trajectories from the mean flow fields obtained by the Massachusetts Institute of Technology general circulation model implemented for the Adriatic
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A minimal model for vertical shear instability in protoplanetary accretion disks Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2021-08-04 Ron Yellin-Bergovoy, Orkan M. Umurhan, Eyal Heifetz
The vertical shear instability is an axisymmetric effect suggested to drive turbulence in the magnetically inactive zones of protoplanetary accretion disks. Here we examine its physical mechanism in analytically tractable “minimal models” in three settings that include a uniform density fluid, a stratified atmosphere, and a shearing-box section of a protoplanetary disk. Each of these analyses show
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Two-dimensional internal gravity wave beam instability. Linear theory and subcritical instability Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2021-08-04 U. Harlander, M. V. Kurgansky
The instability of propagating internal gravity waves (IGWs) is of long-standing interest in geophysical fluid dynamics since breaking IGWs exchange energy and momentum with the large-scale flow and hence they support the large-scale circulation. In this study a low-order IGW beam model is used to delineate both linear and so called non-modal transient instability. In the first part of the study, linear
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Solitary wave diffraction around a concentric porous cylindrical structure in front of a vertical wall Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2021-07-28 Weifeng Ye, Zhenfeng Zhai, Hua Huang
This paper investigates solitary wave diffraction around concentric porous cylindrical structure in front of a vertical wall, where the exterior cylinder is permeable and the interior cylinder is impermeable. This problem is transformed into an issue of bi-directional incident waves diffraction around two concentric cylindrical systems based on the image theory. An analytical solution of the problem
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Introduction Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2021-04-21 Benjamin Favier, Michael Le Bars, Stéphane Le Dizès, Patrice Le Gal, Patrice Meunier
(2021). Introduction. Geophysical & Astrophysical Fluid Dynamics: Vol. 115, Waves, Instabilities and Turbulence in Geophysical and Astrophysical Flows, pp. 231-233.
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Flows in horizontal thermohaline convection with differential diffusion Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2021-03-02 J. A. Whitehead
Oceanographers use the term “differential diffusion” to express a greater value of bulk turbulent diffusivity of temperature within the ocean than the value of bulk diffusivity of salinity, the ratio quantified by Lewis number. Investigation of horizontal thermohaline convection at Prandtl number 1 and infinity over the range 14/3 but insensitive to Pr. Balanced convection at Ra = Ras >106 adopts a
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The merger of two three-dimensional quasi-geostrophic baroclinic tripolar eddies Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2021-02-26 Jean N. Reinaud, Xavier Carton
We investigate the strong interaction between two baroclinic tripolar eddies in a three-dimensional, rapidly-rotating, continuously stratified flow under the quasi-geostrophic approximation. Each tripolar eddy consists of an anticyclonic central vortex with two oblate cyclonic vortices located above and below the anticyclone. The interaction depends on the vertical and horizontal offsets between the
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Weakly nonlinear analysis of mean flow generation for tidally locked exoplanets Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2021-02-04 Steven D. London
We study a model developed by Showman and Polvani [Equatorial superrotation on tidally locked exoplanets. Astrophys. J. 2011, 738, 71–94] to study the behaviour of a thin, upper atmospheric layer of a tidally locked exoplanet; in particular, the behaviour of the atmospheres of “hot Jupiters”, gas giants orbiting close to their stars and tidally locked to them, having a dayside and a nightside. We are
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Viscoelastic Taylor–Couette instability in the Keplerian regime Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2021-02-03 Y. Bai, T. Vieu, O. Crumeyrolle, I. Mutabazi
Instability modes of viscoelastic Taylor–Couette flow in the Keplerian regime are investigated using both linear stability analysis and experimental detection of critical states. A generalised Rayleigh criterion has been derived and it allows to separate the zone of potential purely elastic instability modes and the zone of stability. The analogy between the instability of viscoelastic Taylor–Couette
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Viscoelastic Taylor–Couette instability in the Keplerian regime Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2021-02-03 Y. Bai, T. Vieu, O. Crumeyrolle, I. Mutabazi
Instability modes of viscoelastic Taylor–Couette flow in the Keplerian regime are investigated using both linear stability analysis and experimental detection of critical states. A generalised Rayleigh criterion has been derived and it allows to separate the zone of potential purely elastic instability modes and the zone of stability. The analogy between the instability of viscoelastic Taylor–Couette
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Dynamo action between two rotating discs Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2021-01-22 A. Arslan, A. J. Mestel
Dynamo action is considered in the region between two differentially rotating infinite discs. The boundaries may be insulating, perfectly conducting or ferromagnetic. In the absence of a magnetic field, various well-known self-similar flows arise, generalising that of von Kármán. Magnetic field instabilities with the same similarity structure are sought. The kinematic eigenvalue problem is found to
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Rotational modes of Poincaré Earth models Geophys. Astro. Fluid. Dyn. (IF 1.3) Pub Date : 2021-01-11 B. Seyed-Mahmoud, Y. Rogister
ABSTRACT We study the following rotational modes of Poincaré Earth models: the tilt-over mode (TOM), the spin-over mode (SOM) and free core nutation (FCN), using first a simple Earth model with a homogeneous and incompressible liquid core (LC) and a rigid mantle (MT). We obtain analytical solutions for the periods of these modes as well as that of the Chandler wobble (CW). We show analytically the